sec (6/9): run user-defined scanners in an isolated working directory#30
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jesse-merhi wants to merge 1 commit into
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sec (6/9): run user-defined scanners in an isolated working directory#30jesse-merhi wants to merge 1 commit into
jesse-merhi wants to merge 1 commit into
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The scanner used to run with a working directory derived from the target: the target's parent directory, or the target itself when it was a directory. That handed the scanner writable access to files sitting next to the target, and under Docker that parent became a writable bind mount. Run host scanners in a fresh os.MkdirTemp directory (removed after the run) and keep the Docker cwd empty so nothing target-derived is mounted; the container workdir is already isolated. Removes the now-unused userDefinedScannerCWD helper.
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ClawSweeper status: review started. I am starting a fresh review of this pull request: sec (6/9): run user-defined scanners in an isolated working directory This is item 1/1 in the current shard. Shard 0/1. This placeholder means the worker is alive and reading the current context. I will edit this same comment with the actual review when the claws are done clicking. Crustacean status: shell secured, claws on keyboard, evidence pebbles being sorted. |
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What this changes
Part 6 of 9 in the BYOS security-hardening stack. Stacked on sec (5/9) (#29).
Every process runs with a "working directory" — the folder it's in, which it can read and write by default. Before this change, ClawScan chose the user-defined scanner's working directory from the target:
So scanning
/home/me/skills/suspect/skill.mdran the scanner inside/home/me/skills/suspect/— with write access to everything next to the target. A malicious or buggy scanner could drop or overwrite files beside the thing it was scanning. Under the Docker sandbox this was worse: that parent directory got mounted into the container read-write, turning "scan this file" into "here's a writable mount of its whole folder."The fix
The working directory is no longer derived from the target:
--sandbox off): a freshos.MkdirTemp("", "clawscan-scanner-")directory, deleted after the run. The scanner gets a private scratch dir, not the target's neighborhood."", so nothing target-derived is bind-mounted; the container's own workdir is already isolated.The old
userDefinedScannerCWDhelper (and itsnet/url/path/filepathimports) is removed.Verify
New test
TestUserDefinedScannerUsesIsolatedCwd: scans a file inside a temp dir withSandboxModeOffand asserts the recorded cwd is not the target dir (nor under it) and carries theclawscan-scanner-prefix.